The field of geodesy, the study of the Earth’s shape and its precise measurements, has existed since antiquity. A unique project at TU Delft aims to bridge history, science, and education by reviving a bit of its past. Translating an 1830 thesis originally written in Latin by mathematician Petrus van Galen, the project brings to light early Dutch contributions to gravity research, offering relevant insights for students and researchers alike. Working with TU Delft OPEN Publishing, Assistant Professor Bart Root of TU Delft’s Faculty of Aerospace Engineering was instrumental in bringing this book and some forgotten history to life.
The role of Dutch research
The topic of gravity has played a big part in Assistant Professor Bart Root’s studies and work. It was this expertise that led his then PhD promoter to involve him in a project related to Felix Vening Meinesz, a renowned Dutch geophysicist who became a professor at TU Delft in the late 1930s. Known for his innovative gravity measurement methods, he devised a pendulum apparatus called the “Golden Calf”, which is now part of the Heritage collection at TU Delft’s Library. “We’re very much interested in the Dutch scientific contributions to gravity research, and Vening Meinesz played a huge role,” says Root. The project resulted in the creation of an educational website called Expeditie Wikipedia, highlighting scientific expeditions from the past along with historical perspectives on the science they produced.
Historical motivations
Another member of that project, Marietje Ruijgrok, came across a Latin book from 1830 which contained the terms ‘earth’ and ‘gravity’ in the title. As curator of Trésor, a collection of TU Delft scientific and technological historical items, she was intrigued. Together with Joop Gravesteijn, who was involved with the academic heritage of TU Delft and Stichting De Hollandse Cirkel (an organisation dedicated to promoting the history of geodesy), they asked Root to have a look.
And so began the revival of Disputatio mathematica inauguralis de pendulo ejusque adplicatione ad telluris figuram determinandam (Inaugural Mathematical Discussion on the Pendulum and Its Application to Determining the Shape of the Earth). Written by 19th century Dutch mathematician Petrus van Galen, this forgotten dissertation dealt with the use of the pendulum in determining the shape of the Earth—a significant topic in early geodesy. With an interest in uncovering Dutch contributions to gravity research and a desire to honour the legacy of forgotten figures like van Galen, Root and a team of likeminded individuals set out to translate the thesis into Dutch.
Accurate translation
The translation process itself was no small feat. As Root explains, “It’s very technical and written by a Dutch person who tried to do it in Latin but also used words that didn’t exist back in the day.” Marius Goossens, an expert in classical Latin, took on the challenge of translating the text. Helping with some of the more technical aspects, Root worked with him to create a faithful translation, making van Galen’s work accessible to the public.
The book includes three chapters that are van Galen’s translated thesis. First, van Galen presented a thorough historical description of all the gravity research up until 1830, including data and techniques. Next, he detailed the mathematical concept of how to use a physical pendulum. And finally, he wrote about how to connect the gravity measurements to the shape of the earth. “The data that he collected with his theory and the value of the shape of the Earth he came up with is close to the value that we now know the Earth is,” says Root.
Learning from History
“One of the most important lessons students need to learn is that you always need an uncertainty or precision estimate of your data”
For Root, the translation project also serves as a teaching tool. He incorporates historical perspectives into his lectures, using examples from van Galen’s work to illustrate important lessons in data interpretation. “What van Galen showed is that you can get data from other sources, but if you don’t know the quality of the data, you can reach wrong conclusions,” Root explains.
He uses van Galen’s dissertation to teach students the importance of precision and uncertainty in scientific measurements. By analysing historical data on gravity and the Earth’s shape, van Galen carefully selected only the most reliable measurements, a process that Root believes is crucial for students to understand. “One of the most important lessons students need to learn is that you always need an uncertainty or precision estimate of your data,” he says. “You really need to assess the quality of data before you make conclusions about it, and I think this dissertation shows that.”
Open and accessible
For Root, making scientific work accessible to all is fundamental to advancing knowledge. “I believe science should be open,” he says. “Not only so that everyone can read it, but because it’s good for science itself. It makes science reproducible.” This emphasis on open science aligns with Root’s broader philosophy that data, codes, and research should be freely available for others to verify and build upon.
The involvement of De Hollandse Cirkel was essential in bringing the project to life, providing not only motivational support but also a platform for the project’s eventual dissemination. Root noted that they hope to present the completed book at an upcoming symposium. “Go read it,” he urges. “The book is made by people that are interested in the subject and put time and effort in without being paid, just because they liked the idea. Geodesy is always seen as this stuffy, old type of research, but I think this book shows that there are still a lot of people interested in gravity research.”